Floorlevel motion compensator

ABSTRACT

Drilling by the rotary method is conducted from a floating vessel. The driving joint of the drill string, e.g. a kelly driven by a rotary table or a top joint rotated by a power swivel, includes a splined telescopic joint and hydraulic piston and cylinder means whose pressure is controlled in response to a function of the drill string tension, e.g., dead line tension or cylinder pressure, to maintain desired drill string tension, e. g., constant tension, corresponding to desired bit loading. Motion of exterior part of driving joint relative to vessel is same as that of corresponding joint relative to drill rig operating on land; motion of part of drill string in hole relative to hole is same as that of drill string relative to hole when drilling on land.

I United States Patent Kellner Nov. 4, 1975 [54] FLOORLEVEL MOTION COMPENSATOR 3,088,532 5/1963 Kellner 175/321 X 3,151,686 10/1964 Kammerer 175/27 [75] Jackso" Keune" 3,158,211 11/1964 McCue et a]. 175/85 [73] Assignee: Smith International, Inc., Houston, 312251566 12/1965 Lfaathers 321 X Tex 3,353,851 11/1967 Vincent 1 6/.5 x 3,463,252 8/1969 Miller et al. 175/321 X [22] Filed: Aug. 19, 1974 3,687,205 8/1972 Mori 175/27 [2]] Appl' 498831 Pn'mary Examiner- EmestR. Purser Related U.S. Application Data Assistant Examiner-Richard E. Favreau [63] Continuation of S61. NO. 293,363, Sept. 29, 1972, Attorney 8 Firm-Murray abandoned.

I [57] ABSTRACT U.S. the rotary is conducted from a [51] Int. Cl. E2113 19/08 fl ti vessel. The drivingjoim f the drill String,v f a driven a rotary table 01' a top joint rotated 175/5, 6, 7, 321, 94, 203, 162, 173/4, by a power swivel, includes a splined telescopic joint 150, 148; 254/172, 1 and hydraulic piston and cylinder means whose pressure is controlled in response to a function of the drill [56] References cued string tension, e.g., deadline tension or cylinder pres- UNITED STATES PATENTS sure, to maintain desired drill string tension, e. g., con- 1,938,690 12/1923 Burmist 173/4 x mm tension, corresponding to desired bit loading- 2,598,203 /1952 k r 73 50 Motion of exterior part of driving joint relative to ves- 2,606,003 8/1952 McNeilL'. 175/7 sel is same as that of corresponding joint relative to 2,665,116 1/1954 Brink et al... 173/150 X drill rig operating on land; motion of part of drill 2,810,550 /1957 C ohen 173/72 X tring in hole relative {0 hole is same as that Of 2,838,283 6/1958 Simmonds et a1. 175/321 X string relative to hole when d i i on ]and 2,847,188 8/1958 Wlltse 173/150 0 2,937,129 6/1961 Webb 175/321 x 28 Claims, Flgllres l}? I! a: if mmraum 31 /0/ m7 I M] 5/ [07 o 23 Va;

U.S. Patent Nov. 4, 1975 Sheet 2 of7 3,917,006

U.S. Patent Nov. 4, 1975 Sheet 3 of7 3,917,006

US. Patent NOV.4, 1975 Sheet40f 7 3,917,006

Sheet 5 of 7 U8. Patent Nov. 4, 1975 US. Patent Nov. 4, 1975 I sheet 6 on 3,917,006

US. Patent -Nov. 4, 1975 Sheet 7 of 7 I and kelly bushing.

FLOORLEVEL MOTION .COMPENSATOR This is a continuation of application Ser. 'No.

" 293,363, filed Sept. 29, 1972, now abandoned.

BACKGROUND OF THE INVENTION .drill bit equal to the weight of the drill string below the telescopic joint. To vary the bit weight it is necessary to pull the drill string and relocate the telescopic joint.

It is also known to compensate for the rise and fall of a floating vessel on which a drill rig is mounted by raising and lowering the travelling block from which the drill string is suspended, the travellingblock being raised and lowered automatically so as to maintain constanttension in the line supporting the travelling block.

When a down hole splined telescopic joint or bumper sub is used as a motion compensator, the part of the drill string above thesub is constantly moving up and down in the hole; in addition, the position of the lower part of the sub relative to the upper part of the sub is unknown, so that the travel range of the sub may be exceeded causing the drill bit to lift off bottom or the weight of the upper part of the drill string to be periodically imposed on the drill bit.

When a block motion compensator is used, there is a 7 huge part moving up and down relative to the rig floor;

it is difficult to work underneath this moving part. In addition, the kelly is constantly moving up and down in the kelly bushing causing increased wear on the kelly In one known type of block tion device; this passive arrangement may get out of phase with the motion causing loss of effective compensation.

A few examples of prior art devices are shown in United States patents:

(a) Cable Tensioner PrudI-lomme et al Hydraulic cylinders are of course well known and have been used for a variety of purposes in connection motion compensator, an 1 fair spring or large tank full of air is used to provide 'a fairly constant pressure for actuating'the block mo- 2 with drill strings, e.g., in hydraulic pulling fishing tools (see US. Pat. Nos. 2,190,442, 2,377,449, 2,537,413),

in hydraulic jars (see U.S. patents 1,637,505 and 2,499,695 in hydraulic bit loading devices (see US. Pat. Nos. 3,298,449 and 3,180,437) and cited art relative to the foregoing patents.

' SUMMARY OF THE INVENTION According to the invention, a hydraulic cylinder is incorporated into the driving joint of a drill string and is actuated in response to the drill string tension, e.g., as measured by a load cell in the dead line or by the fluid pressure in the cylinder, to maintain the desired weight on the bit. The driving joint may be either a kelly, which is turned by a rotary table, or an uppermost joint of drill pipe turned by a power swivel. In either case, the beneficial result is obtained that workmen on the floating vessel see a kelly ortop joint that behaves relative to the floating vessel the same as such driving joint behaves relative to a drill rig on land; there is no motion of such driving joint and the supporting swivel and travelling block and cable relative to the floating vessel .caused by rise and fall of the vessel with and in the water. At the same time the portion of the drill string in the hole and up to the driving joint behaves relative to the hole the same as a drill string behaves relative to the hole. when operated-by a drill rig on land; there is no loss of contact between the bit and the hole bottom nor loss of weight on the bit when the floating vessel rises, nor any increase of weight on the bit nor any compression of the drill string when the floating vessel falls.

Placement of the parting line between the vessel and the hole oriented parts of the drill string in the driving joint which is adjacent the rig floor or vessel deck and employing a hydraulic cylinder in the driving joint actuated to maintain constant tension in the hole oriented part of the drill string achieve the foregoing beneficial result. To effect actuation of the hydraulic cylinder without interference with the normal functioning of the driving joint of the drill string, be it kelly or top joint or drill pipe, the fluid lines supplying pressure for operating the hydraulic cylinder are disposed inside the driving jointwhereby the exterior can cooperate with a totary table, in the case of a kelly, or at least be less subject to damage when passing through .the holein the vessel floor or slip support member in the case of a power swivel driven top joint. The'invention provides a driving joint and motion compensator in one unit disposed between .the swivel and the regular drill pipe. The exterior of the unit remains axially stationary relative to the kelly bushing or floor aperture despite verticalmotion of the vessel, except for the normal on land type of axial motion, due to making hole or adding joints of regular drill pipe or coming out of the hole to change bits and reentering, being present. For brevity the combined driving joint and motion compensator may be called a hydraulic driving joint, e.g., a hydraulic kelly or a hydraulic top joint.

' BRIEF DESCRIPTION OF THE DRAWINGS 3 and suspension apparatus;

FIG. 3 is a view similar to FIG. 2 showing a modification utilizing a power swivel driving a hydraulic top joint;

FIGS. 4A, 4B, and 4C, together show in detail the hydraulic kelly of the system shown in FIGS. 1 and 2;

FIGS. 5 through 12 are sections and views taken at the planes indicated on FIGS. 4A-C and 8; and

FIG. 13 is a schematic drawing showing an electrohydraulic control circuit for a hydraulic driving joint.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 there is shown a conventional floating vessel 21 including a deck 23 connected to and supported by legs 25 extending down below the air-water interface 27 into the water 29 where they are connected to and supported by pontoons 31. The pontoons are connected to cables 33 whose lower ends are anchored in the earth 35. Although only two legs 25 and pontoons 31 are shown, it will be understood that FIG. 1 is an elevational view and that additional legs or other support means are or may be provided as necessary or desirable to support deck 23 above water in the air 37.

Surmounting and connected to the vessel deck 23 is a conventional drill rig derrick comprising a rig floor 39 supported by legs 41 connected to deck 23 and carrying derrick legs 43 supporting derrick top 45. The derrick includes a hoist comprising crown block 47, travelling block 49, and cable 51 looped around the blocks. One end of the cable, dead line 53, in which is connected a load cell 55, is anchored to the rig floor at 57.

The other end of the cable, at 59, is wound on a conventional motor driven drum or winch, e.g., drawworks 61, whereby the hoist can be raised or lowered.

Beneath the floating vessel 21 in the earth 35 is borehole 63 in which in the conventional manner is set surface casing 65 extending up to the earthwater interface 68 where it is connected to a conventional blowout preventer 67, ball joint 69, and riser or conductor casing 71. The latter extends above the air-water interface 27 to a level spaced below deck 23 sufficient so that it will not be struck by the deck when the vessel moves down with or in the water for any reason. The rise'r is maintained in tension by being connected to cables 73 passing over pulleys 75 and connected to weights 77, all in a heretofore known manner.

Also in conventional fashion, a mud casing 79, atfixed to the deck 23 of the floating vessel, is telescoped into the upper end of riser 71 and sealed thereto by sliding seal 81 whereby fluid communication is maintained between the riser and mud casing as the vessel rises and falls. The ball joint 69 allows for lateral movement of the vessel 21 relative to the hole 63 while maintaining fluid communication between the surface casing 65 and riser 71.

Between travelling block 49 and the bottom 83 of borehole 63 is disposed a drill string which is conventional except for the inclusion of the hydraulic driving joint, in this case a hydraulic kelly 85, instead of other separate driving joint and motion compensator. The drill string includes drill bit 87, drill collars 89, a plurality of joints of drill pipe 91, hydraulic driving kelly 85, and swivel 93, the latter being suspended by bail 95 from hook 97 on the travelling block 49. Mud is supplied to the drill string in the conventional manner from mud tank 101 and mud pump 103 via flexible mud line 4 105 to swivel After being pumped down the drii. string, out through drill bit 87, and back up the hole 63 and riser 71 to mud casing 79, the mud returns to the tank via pipe 107.

Referring now to FIG. 2, the hydraulic kelly includes a tubular mandrel 111 having a threaded pin 113 (see FIG. 4C) at its lower end. The pin includes an unthreaded neck 1 12 and a shoulder 1 14 forming conventional rotary shouldered connection means to transmit torque and form a seal. Pin 113 is screwed into correlative rotary shouldered connection means comprising threaded box 115 at the upper end of the topmost joint of regular drill pipe 91. The mandrel 111 extends into tubular body 117, the exterior of which is of square or other non-round cross-section to provide drive surface means 119 to cooperate with kelly bushing 121 in rotary table 123. The mandrel is splined to the body 1 17, providing means to transmit torque from the body to the mandrel. The mandrel is provided with spline means moving in a spline means portion of the body, providing means to transmit torque from the body to the mandrel. The mandrel is provided with piston means moving in a cylinder portion of the body, providing means to exert fluid pressure acting upwardly on the mandrel.

The body 117 has a tubular stem 125 provided at its upper end with a threaded box 127 (see FIG. 4A) receiving a threaded pin 129 on the lower end of the rotating part 131 of swivel 93 (or of a swivel sub connected thereto). The stem has an axial flow passage which is telescopically connected by a wash pipe 133 (see FIGS. 4A and 413) to mandrel lll, whereby mud can flow down through the hydraulic kelly from the swivel 93 to the drill pipe 91. Box 127 includes a smooth sealing face 126 at its end and an unthreaded portion 128 adjacent thereto, providing rotary shouldered connection means to seal with pin 127, like the connection between pin 113 and box 115 at the other end of joint 85.

As will be described in detail later, the stern 125 also has a plurality of off-axial flow passages opening at their lower ends to the cylinder portion of body 117, below the several piston means on the mandrel, and opening at their upper ends into upper and lower portions of dual fluid chamber 135 rotatably mounted therearound. Hydraulic fluid lines 137, 139 are connected to chamber 135 through various valving as will be described in connection with FIG. 13.

From the foregoing, it will be seen that the hydraulic kelly includes a tubular body having a tubular stem affixed thereto extending upwardly through and rotatable within a fluid chamber, a tubular mandrel extending down from within the tubular body, the mandrel and body being splined together and also provided with cooperating piston and cylinder means, the tubular body being further provided with drive surface means for cooperation with a kelly bushing, and rotary shouldered connection means at the lower end o f'the body and upper end of the mandrel.

As shown in FIG. 3, the foregoing structure can be used as a hydraulic top joint 140. The apparatus of FIG. 3 is the same as that of FIGS. 1 and 2 except that no rotary table is used, the drill string being rotated by hydraulic motor 141, geared transmission 143, and gear sub 145, all together known as a power swivel. Hydraulic fluid for the power swivel is supplied through flexible conduits 144, 146. Hydraulic top joint 140 is the same as hydraulic kelly 85 except that the tubular body 147 of the hydraulic top joint has a circular outer periphery, omitting the drive surface means of the hydraulic kelly shown in FIGS. 1 and 2. The drive surface means is instead provided by the gear 148 on sub 147. Instead of the kelly bushing of FIGS. 1 and 2, an apertured plate 149 may be placed in fixed table 151 in floor 39 to partially seal off the space between the table and body. Other elements in FIG. 3, being the same as in FIGS. 1 and 2 are given like reference numbers. Since the hydraulic top joint of FIG. 3 is otherwise the same as the hydraulic kelly of FIGS. 1 and 2, it will not be described further, for its details are the same as those of the hydraulic kelly whose details will next be described. It is to be noted however that the rotary shouldered connection 127, 145 of FIG. 3 must transmit torque in addition to transmitting axial loads and providing a seal to transmit high pressure mud.

Referring now to FIGS. 4A, 4B, 4C, and FIGS. 5-12, the hydraulic kelly 85 includes tubular body 117 which has externally cylindrical end portions 161, 163 with a generally square cross section portion 165 therebetween providing flat drive surface means 119. The inner periphery of the tubular body 117 is of square cross section for most of its length, as shown at 167 in FIGS. 6-8 and 10-11. This enables the body 117 to transmit torque to body liner means 169.

The liner means 169 includes several tubular members i.e., 171, 173, 175, 177, abutting each other end to end, together with threaded bushing 179 screwed into the lower end of body 117 to support the rest of the liner means. The upper end of the liner means is held down by square flange 181 on stem 125, the latter being held down in the body by threaded bushing 183 screwed into the upper end of the body. A snap ring 184 locks bushing 179 in place.

Liner member 171 has a square cross section outer periphery fitting snugly within the body 117; the upper end of member 171 is threadedly connected and sealed to liner member 173 at 185.

As shown in FIG. 10, liner member 173 has a generally square cross-section outer peripherybelow shoulder 187 (FIG. 4B), and a circular cross-section outer periphery above shoulder 187, as shown in FIG. 7. These are slots 191, 193 in the upper end of liner member 173. The circular cross-section outer periphery of the upper portion of liner member 173 causes same to have the form of a cylindrical tube portion 173' (FIG. 48), between which and the inner periphery of the body 117, as shown in FIG. 7, are left a plurality of corner spaces 195.

Liner member 175, which, as shown in FIG. 4B, rests on top of tube portion 173' has, as shown in FIG. 7, a square cross-section outer periphery snugly received in body 117. The upper end ofliner member 175 is of circular cross section so as to telescope within the lower At the lower end of body 117, as shown in FIG. 4C, I

sliding seal means 211 is provided cooperating with smooth cylindrical external surface 213 on mandrel 111. Seal means 211 comprises a short metal tube 215 captured between an intumed lip 217 on bushing 179 and the lower end of liner member 171. Vulcanized to the inner periphery of tube 215 is elastomeric, e.g., rubber, sealing material sleeve 219. For further details of this sea] means see US. Pat. No. 3,232,186.

Liner member 173 is provided on its inner periphery with axially extending splines 221 which mesh with axially extending splines 223 on the exterior of mandrel 111, providing spline means to transmit torque between the mandrel and liner member 173, and hence between the mandrel and body 117, while allowing relative axial motion therebetween.

As shown in FIG. 4B, mandrel 111 is made of several tubes 225, 227, 229, 231 screwed together end to end, the splines 223 being on lowermost tube 225. Mandrel tube 227 is provided on its exterior with a piston 233, the piston including an enlargement or hub 235 to the exterior of which is vulcanized an elastomeric, e.g., rubber, sliding seal means sleeve 237, similar to sleeve 219. Piston 233 slides axially within the smooth cylindrical inner surface of tube 173' which forms a cylinder.

Referring now also to FIG. 4C, mandrel tubes 227 and 225 provide a piston rod 238. The annular space 239 (FIG. 48) formed between the piston rod and liner tubes 173, 171, is closed at its upper end by piston 233 and at its lower end by seal means 211. The piston rod 238, liner tubes 173, 171, piston 233, and seal means 211 thus form a first piston and cylinder means to apply axial upward force to the mandrel 111. Means for admitting hydraulic pressure fluid to the space 239 will be described later.

Referring to FIG. 4B, mandrel tube 229 has a cylindrical outer periphery 241 which seals with sliding seal means 243. Seal means 243 includes a metal tube 245 pressed into liner tube 175 against shoulder 247 and an elastomeric, e.g., rubber, sleeve 2S1, vulcanized thereto, similar to sleeve 219.

Cemented to the ends of liner tube 175 are steel fibre annular pads 253, 255 which provide bumper stop means for cushioning the piston 233 at the upward limit of travel of the mandrel 111 relative to body 117 and cushioning bumper sleeve 257 which limits the downend of liner member 177 to which it is sealed by an O- ring.

Liner member 177 has upper and lower end portions of square cross-section outer periphery which, like liner member 175, fit snugly within body 1 17. The middle part of liner member 177 is of circular cross-section outer periphery forming a cylindrical tubular portion 177' which like tubular portion 173' is spaced from the inner periphery of body 117 leaving corner spaces therebetween similar to corner spaces 195. The upper end of liner member 177 is slotted at 197 similar to slots 191, 193 at the upper end of tubular portion 173 (FIG. 77).

ward travel of the mandrel. Bumper sleeve 257 is captured between shoulder 259 on mandrel tube 229 and the lower end of mandrel tube 231. Bumper sleeve 257, stop means 255, 253, and the upper end 261 of piston 233 provide stop means limiting relative axial travel of the mandrel l 11 and the kelly body 117. The lower end of liner tube is of circular outer periphery providing a neck 258 which extends down into cylinder tube 173 to stop piston 233 before it runs past the end of tube 173.

Referring to FIGS. 48 and 4A, mandrel tube 231 is provided on its exterior with a piston 263, the piston including an enlargement or hub 265 to the exterior of which is vulcanized an elastomeric, e.g., rubber, sliding seal means 267, similar to sleeve 219. Piston 263 slides 7 axially within the smooth cylindrical inner surface of tube 177' which forms a cylinder.

Referring to FIG. 4B, mandrel tubes 231 and 229 provide a piston rod 268. The annular space 269 formed between the piston rod 268 and liner tube 177 is closed at its upper end by piston 263 and at its lower end by sea] means 243. The piston rod 268, liner tube 177, piston 263, and seal means 243 form a second piston and cylinder means to apply axial force to mandrel 111. Means for admitting hydraulic pressure fluid to the space 269 will be described later.

The first and second piston and cylinder means form tandem piston and cylinder means, whereby the outer diameter of the hydraulic kelly can be smaller than would be needed to apply the same force with a single piston and cylinder means. Additional piston and cylinder means can be added to the tandem piston and cylinder means as may be necessary to apply the prescribed force, or only a single piston and cylinder means can be employed if that is sufficient to meet the force requirements.

Referring to FIG. 4A, at the upper end of piston hub 265 is sliding seal means 271 comprising metal tube 273 screwed into hub 265 and an elastomeric, e. g., rubber, sleeve 275, vulcanized to tube 273, similar to the construction of seal 211. Seal means 271 engages and seals with the smooth cylindrical outer periphery 277 of wash pipe 133. Wash pipe 133 is screwed into stern 125 at 279. Seal means 271 and wash pipe 133 provide telescopic means connecting the mandrel 111 to the stern 125 of body 117 to transmit pressure fluid, e.g., mud, therebetween.

Referring to FIGS. 4A and 5, to conduct hydraulic pressure fluid, e.g. an oil, to the tandem piston and cylinder means, four axially extending passages 281, 283, 285, 287 are provided in stem 125. Each of these passages includes a plurality of interconnecting bores terminating at their upper ends in radial ports 289, 291, 293 295. Ports 289, 293 are colevel and open into upper annular space 297 in chamber 135. Ports 295 and 291 are colevel and open into lower annular space 301 in chamber 135. Spaces 297 and 301 are separated from each other by annular seal 303 mounted in a groove in chamber collar 311. Seal 303 engages and seals with the smooth cylindrical outer periphery 305 of stem 125. Spaces 297 and 301 are separated from the atmosphere by annular plugs 307, 309 which are screwed into the ends of the tubular collar 311 chamber 135. The plugs carry annular seals 313, 315 which engage and seal with the outer surface 305 of the stem 125. Plug 307 is sealed to collar 311 by packing material ring 314. Plug 309 is sealed to collar 311 by metal to metal tapered seal 316.

Combined radial and thrust bearings 317, 319 have their inner races pressed onto stem 125 and their outer races captured between the respective plugs 307, 309 and shoulders 321, 323 on chamber collar 311. By means of the bearings the chamber 135 is axially supported on stem 125 and the stem is rotatable therewithin.

Stem 125, for ease of manufacture, includes upper and lower portions welded together at 325.

Hydraulic lines 137, 139 are screw connected to ports 327, 329 in chamber collar 311; the ports 327, 329 communicate with spaces 297 and 301 respectively. By the foregoing means hydraulic line 137 communicates with stem passages 281 and 285, and hydraulic line 139 communicates with stem passages 283 and 287. As shown in FIG. 6 the lower ends of passages 281, 283, 285, 287 are connected to hydraulic lines or pipes 331, 333, 335, 337. To make sure that the proper passages and pipes are connected to the proper spaces 297, 301 in the manifold during assembly, the liner tube 177 is provided with an alignment pin 339 engaging a slot 341 in kelly body 117. Hydraulic lines 331, 335 extend down through corner spaces between the mandrel and cylinder 177' and through holes in square cross-section portion of liner tube 177 and, as shown in FIG. 7, through holes in the corners of liner tube and on down through comer spaces between cylinder 173 and the mandrel into passages 343, 345 in the square cross-section part of liner tube 173 where, as shown in FIG. 9, they are sealed. As shown in FIGS. 8 and 9, passages 343, 345 connect to radial ports 347, 349 which communicate with pressure fluid space 239 of the lower piston and cylinder means. In similar fashion, hydraulic lines 333, 337 extend down into passages in the square cross section part of liner tube 177 connecting to radial ports therein (not shown) which communicate with pressure fluid space 269 of the upper piston and cylinder means.

In order to permit easy movement of the kelly mandrel 111 relative to the kelly body 117 under the influence of the tandem piston and cylinder means it is necessary to vent the space 351 (FIG. 4B) between the lower piston 235 and the upper seal means 243. This is effected by passage means including slots 191, 193 (FIGS. 4B and 7), corner spaces (FIG. 7), corner passages 353, 355 between liner tube 175 and kelly body 117 which extend up between the square crosssection part of liner tube 177 and kelly body 117 to the annulus 357 between cylinder tube 177' and kelly body 177 and through slots 359, 361 in the upper square cross section part of liner tube 177 to slots 197, 198 in the upper end of liner tube 177 to space 363 between the upper end of mandrel 111 and the lower end of stem 125, and thence through radial passages 365 in stem 125 to the exterior of stem 125 above flange 181 thereof to vertical vent passages 367 in bushing 183.

Referring next to FIG. 13, there is shown the hydraulic circuit for controlling the supply of hydraulic fluid to the tandem piston and cylinder means whereby constant tension in mandrel 111 is maintained. Hydraulic pump 371 supplies pressure liquid from reservoir tank 373 through line 374, metering valve 375, and line 376 to the right hand side of pilot cylinder 377. The section and volume of the right hand side of pilot cylinder 377 is equal to that of space 239 of the lower piston and cylinder means of hydraulic kelly 117. Liquid supplied to the right hand side of cylinder 377 moves piston 379 to the left forcing liquid into hydraulic line 139 and thence through pilot valve 381 to space 239 in the lower piston and cylinder means of the hydraulic kelly. This causes the mandrel 111 to be elevated to tension the drill pipe 91 and reduce the weight on bit 87. If the weight of the drill string is larger than can be supported by the lower piston and cylinder means of the hydraulic kelly 85, hand actuated valve 385 is moved to the position shown in the drawing so that pressure liquid from line 376 is also supplied to space 269 of the upper piston and cylinder means of kelly 85 through hydraulic line 137. Incidentally, the area of upper piston 263 is slightly larger than that of lower piston 233 because of construction requirements.

The pressure on the downstream side of metering valve 375 is bled off of line 376 through line 389 to electro-mechanical transducer 391 which produces an electric output, e.g., voltage, proportional to the pressure input. Such output is fed to comparator 393 which compares the electric output of transducer 391 with the adjustable electric output, e.g., voltage, of electric generator 395. If the outputs are equal, the metering valve 375 receives a control signal (which may be zero) from comparator 393 via cable 397 which moves the valve 375 to its middle or blocked position and no further actuating liquid is fed to the piston and cylinder means of the kelly.

If the pressure in line 389 rises or falls, as indicated by pressure gage 399, comparator 393 sends corresponding signal to valve 375 causing it to move down or up, respectively, to bleed liquid from the piston and cylinder means to the left hand side of pilot cylinder 377 and to tank 401 or to add more liquid to the piston and cylinder means.

If it is desired to increase or decrease the weight on the bit, the output of generator 395 is adjusted up or down, respectively. If it is desired to extend or retract the kelly fully, the generator output can be adjusted to zero or to supply an output beyond the range of pump 371. The output pressure of pump 371, which is adjustable, is normally set a little higher than pressure of full drill string weight. Relief valve 403 prevents excessive pressure being imposed on the hydraulic system, dumping to tank 405 whenever the maximum pressure for which it is set is exceeded.

The movement of the piston of the lower piston and cylinder means relative to its range of travel is equal to that of piston 379 relative to pilot cylinder 377. Piston rod 407 connected to piston 379 actuates potentiometer 409 which varies the current flowing to galvanometer 411. The scale of the galvanometer is calibrated to indicate travel of the piston 233, i.e., its position relative to kelly body 117.

The pilot cylinder 377, potentiometer 409, and galvanometer 411 thus provide position indicator means. Without such means, line 376 could be connected directly to space 239 of the lower piston and cylinder means of the kelly. To synchronize the position indicator means with the lower kelly piston, reversing valve 413 is moved to a position opposite to that shown in the drawing. This supplies fluid from pump 371 via line 415, pressure reducing valve 417, valve 413, and line 419 to pilot actuated valve 381, moving the latter from the position shown to the opposite position. In the latter position valve 381 allows the left hand side of pilot cylinder 377 to dump to tank 421, which causes piston 379 to be moved all the way to the left end of cylinder 377. At the same time the space below piston 233 is connected via valve 381, line 423, pilot actuated check valve 425 (opened by the pressure in line 419), and line 415 directly to pump 371, by passing pilot cylinder 377 and metering valve 375. This causes the piston 233 (and also piston 263) to move up in cylinder 117 to the limit of their travel. Reversing valve 413 is then returned to the position shown in the drawing and the system is ready to operate with the position indicator means synchronized.

Alternative to the use of pressure in the line 376 to control comparator 393, a signal can be obtained from the conventional weight indicator 55 in dead line 53. Such weight indicator may include a sheave 427 around which passes the dead line 53. An arm 429 connected to turn with the sheave bears on a diaphragm chamber 431 to vary the pressure therein according to the tension in the dead line. The pressure of the chamber 431 is conducted by pipe 433 to Bourdon tube pressure gage 435, calibrated to indicate weight on bit 87. The pressure in pipe 433 is also conducted by pipe 437 to electro-mechanical transducer 439 to produce an electric output which is fed by cable 441 to comparator 393.

The control circuit shown in FIG. 13 provides the control means or controller 450 shown connected to hydraulic lines 137, 139 in FIGS. 1, 2, and 3. Although the FIG. 13 controller is preferred, it is but one of many which can be devised to control the hydraulic driving joints shown in FIGS. 1 through 12 to supply pressure fluid thereto in response to changes in line tension. For example controllers responsive to line tension for controlling linear actuators are shown in the afore-listed prior art US. Pat. No. 3,421,581 (Van Gejn), 3,653,635 (Bates), 27,261 (Grommell et al). The FIG. 13 controller is the join invention of the present applicant and George A. Alther, and its details are not to be considered part of the sole invention of applicant herein claimed, but merely as representative of a preferred form of controller which can be used as an element of the present applicants sole invention.

While a preferred embodiment of the invention has been shown and described many modifications thereof can be made by one skilled in the art without departing from the spirit of the invention.

The apparatus heretofore described, though operated automatically, could be operated manually. The method involved includes application to the telescopic hydraulic driving joint hydraulic fluid of a predetermined pressure equal to the desired line tension and thereafter maintaining that pressure constant independent of the effects of rise and fall of the floating platform. Preferably however the method is carried out automatically by controller 450. As the platform falls tending to lower the pressure in the joint, thereby tending to increase the bit weight and lower the line tension, the controllers comparator 395 senses the drop in pressure and causes metering valve 375 to add more hydraulic fluid to the joint to bring the joint pressure back up. When the platform rises, valve 375 is moved to bleed off fluid to keep the pressure from rising. The joint itself can be built to accommodate any expected range of rise and fall of the drilling platform. A joint capable of expanding 15 feet from its fully contracted position would be normal.

I claim:

1. A hydraulic driving joint comprising a tubular body providing an axial passage therethrough,

a tubular mandrel axially slidably disposed in said passage in said body. first means interconnecting the body and mandrel to transmit torque therebetween relative to the tube axes while allowing relative axial motion therebetween,

second means interconnecting the body and mandrel to receive pressure fluid and thereby to apply axial force to the mandrel third means interconnecting the body and mandrel to transmit drilling fluid from the body to the mandrel,

first connection means for connecting an end of the body at one end of the joint to a drilling fluid conduit and to means for raising and lowering the joint,

1 1 second connection means for connecting an end of the mandrel at the other end of the joint to a drill string for transmitting drilling fluid between the joint and drill string and for transmitting forces therebetween for raising and lowering and turning the drill string, and means connectable to a suitable source for conducting to said second means actuating fluid different from said drilling fluid.

2. Joint according to claim 1 including a stern on said body at said one end of the joint providing said first connecting means.

3. Joint according to claim 1 wherein said second means interconnecting said body and mandrel is tandem piston and cylinder means, and including off axial fluid passage means in said body to vent the space between different ones of said piston and cylinder means.

4. Joint according to claim 1 including cushion means to limit the axial travel of said mandrel relative to said body.

5. Joint according to claim 1 in combination with drive surface means for rotating said body.

6. Joint according to claim 5 wherein said drive surface means is on the exterior of said body which is of non-circular cross-section outer periphery.

7. Joint according to claim 1 wherein said means for conducting actuating fluid includes passage means inside said body extending alongside of but exterior to said axial passage 8. Joint according to claim 7 in combination with drive surface means for rotating said body.

9. Joint according to claim 8 wherein said drive surface means is on the exterior of said body and is of noncircular cross section.

10. Joint according to claim 7 wherein said means for conducting actuating fluid further includes rotatable connection means to connect the actuating fluid passage means in the body to a source of actuating fluid while allowing rotation of the body relative to said source.

11. Joint according to claim 10 wherein said body includes a tubular stem at said one end of said joint forming a passage for drilling fluid, said stem providing said first connecting means, said rotatable connection means including said stem, annular chamber means through which extends said stem rotatable therewithin, hydraulic line means connected to said chamber means, and off axial actuating fluid passage means in said stem alongside of said drilling fluid passage and communicating with said chamber means.

12. Joint according to claim 11, said third means including a wash pipe connected to said stern extending telescopically into said tubular mandrel in sealing, axially slidable, fluid communicating relationship with said mandrel and the drilling fluid passage in said stem.

13. Joint according to claim 11 further including off axial actuating fluid passage means in said body connected to said off axial actuating fluid passage means in said stem and to said second means interconnecting said body and mandrel to apply axial force to said mandrel, the latter means being piston and cylinder means.

14. Joint according to claim 13 including liner means in said body providing said axial passage therethrough and providing body portions of said first and second means interconnecting said body and mandrel. said off axial fluid passage means in said body lying between the inner periphery of said liner means and the inner periphery of said body.

15. Joint according to claim 1 including tubular liner means inside said body connected to said body to prevent relative axial and rotational motion therebetween and providing said axial passage therethrough and providing body portions of said first and second interconnecting means.

16. Joint according to claim 15 wherein said first means interconnecting said body and said mandrel includes splines on said liner means engaging splines on said mandrel.

17. Joint according to claim 15 wherein said second means interconnecting said body and said mandrel includes piston means on said mandrel and cylinder means on said liner means and sliding seal means on said liner means engaging piston rod surface means on said mandrel.

18. Joint according to claim 15 wherein said liner means includes portions of square cross-section outer periphery fitting snugly with portions of said body of square cross-section inner periphery.

19. Joint according to claim 1 in combination with means to supply pressure fluid to said second means interconnecting the body and mandrel, a drill rig including means to rotate and suspend the driving joint, and means dependent on the load on said second connection means to control the supply of said pressure fluid to said second means interconnecting said body and mandrel.

20. Combination according to claim 19 wherein said means to control the supply of said pressure fluid to said second means interconnecting the body and mandrel causes said second means interconnecting the body and mandrel to produce an axial force on said mandrel acting opposite to the load on said second connection means to maintain an adjustable selected load on said said second connection means.

21. Joint according to claim 1 in combination with a power swivel connected to said first connection means.

22. Joint according to claim 21 wherein both of said connection means are rotary shouldered connections.

23. Joint according to claim 1 wherein said body is of kelly conformation on its exterior and in combination with a kelly bushing axially slidably mounted on said kelly adapted to transmit torque thereto.

24. Joint according to claim 23 wherein at least the second one of said connection means is a rotary shouldered connection.

25. In a rotary drilling apparatus,

a string of drill pipe,

a hoist carrying a swivel including a part rotatable relative to the hoist, and

a combined driving joint and axial motion compensator means connected between the string of drill pipe and said rotatable part of the swivel to allow relative axial motion of the string of drill pipe. and swivel and at the same time transmit fluid and axial force and torque therebetween,

said combined driving joint and axial motion compensator means being disposed adjacent the swivel at the uppermost end of the string of drill pipe.

26. In a rotary drilling apparatus, a string of drill pipe, a hoist carrying a swivel including a part rotatable relative to the hoist, a combined driving joint and axial motion compensator connected between the drill pipe and said rotatable part of the swivel to allow relative motion of the pipe and swivel and at the same time transmit fluid and force therebetween, said driving joint being disposed adjacent the swivel at the upper end of said drill pipe,

said compensator means including piston and cylinder means transmitting axial load from the pipe to the rotatable part of the swivel, and

means to maintain constant the force exerted by said piston and cylinder means and thereby to maintain constant tension on said hoist.

27. In the method of drilling an earth bore from a floating platform thereabove with a rotary drilling apparatus,

said apparatus including: on the platform a hoist having a movable portion movable up and down relative to the platform, in the earth bore a drill pipe with a drill bit at the lower end thereof, and means intermediate the drill pipe and said movable portion of the hoist providing a connection between the drill pipe and said movable portion of the hoist to take some of the weight of the pipe off the bit and providing for rotating the pipe and transmitting drilling fluid via the pipe between the upper end of the pipe and the drill bit,

said method comprising:

rotating the drill pipe, and

14 via the drill pipe and the annulus thereabout circulating drilling fluid down to the drill bit and back up again, the improvement comprising: providing a hydraulic retractable telescopic driving joint in said connection between said movable portion of the hoist and the drill pipe applying to the telescopic driving point hydraulic fluid of a pressure equal to a prescribed pressure, and

maintaining said pressure constant independent of rise and fall of said platform,

whereby said movable portion of the hoist and any other portions of said drilling apparatus connected between said movable portion of the hoist and said joint move relative to the platform only the same as if there were no rise and fall of the platform.

28. The combination of claim 25 wherein said driving joint is a kelly having exterior configuration means thereon for engaging with rotary drive means allowing torque transmission therethrough while permitting relative axial movement therebetween.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,917,006 DATED November 4, 1975 INVENTOR(S) Jackson M. Kellner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 40, change "or (second occurrence) to --of-.

Column 5, line 44 change "These" to -There.

Column 5, line 68, change "77" to 7-.

Column l0,.line 18, before "27,261" insert --Re.

Column 10, line 19, change "join" to joint--. 4

Column .14, line 8, change "point" to --joint.

Column 8, line 35, change "'177" to ll7-.

Column l2, line 36, cancel "said" (second occurrence) Signed and Scaled this Seventeenth Day Of August 1976 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Arte-fling Office Commissioner nfPatenls and Trademarks 

1. A hydraulic driving joint comprising a tubular body providing an axial passage therethrough, a tubular mandrel axially slidably disposed in said passage in said body. first means interconnecting the body and mandrel to transmit torque therebetween relative to the tube axes while allowing relative axial motion therebetween, second means interconnecting the body and mandrel to receive pressure fluid and thereby to apply axial force to the mandrel third means interconnecting the body and mandrel to transmit drilling fluid from the body to the mandrel, first connection means for connecting an end of the body at one end of the joint to a drilling fluid conduit and to means for raising and lowering the joint, second connection means for connecting an end of the mandrel at the other end of the joint to a drill string for transmitting drilling fluid between the joint and drill string and for transmitting forces therebetween for raising and lowering and turning the drill string, and means connectable to a suitable source for conducting to said second means actuating fluid different from said drilling fluid.
 2. Joint according to claim 1 including a stem on said body at said one end of the joint providing said first connecting means.
 3. Joint according to claim 1 wherein said second means interconnecting said body and mandrel is tandem piston and cylinder means, and including off axial fluid passage means in said body to vent the space between different ones of said piston and cylinder means.
 4. Joint according to claim 1 including cushion means to limit the axial travel of said mandrel relative to said body.
 5. Joint according to claim 1 in combination with drive surface means for rotating said body.
 6. Joint according to claim 5 wherein said drive surface means is on the exterior of said body which is of non-circular cross-section outer periphery.
 7. Joint according to claim 1 wherein said means for conducting actuating fluid includes passage means inside said body extending alongside of but exterior to said axial passage.
 8. Joint according to claim 7 in combination with drive surface means for rotating said body.
 9. Joint according to claim 8 wherein said drive surface means is on the exterior of said body and is of non-circular cross section.
 10. Joint according to claim 7 wherein said means for conducting actuating fluid further includes rotatable connection means to connect the actuating fluid passage means in the body to a source of actuating fluid while allowing rotation of the body relative to said source.
 11. Joint according to claim 10 wherein said body includes a tubular stem at said one end of said joint forming a passage for drilling fluid, said stem providing said first connecting means, said rotatable connection means including said stem, annular chamber means through which extends said stem rotatable therewithin, hydraulic line means connected to said chamber means, and off axial actuating fluid passage means in said stem alongside of said drilling fluid passage and communicating with said chamber means.
 12. Joint according to claim 11, said third means including a wash pipe connected to said stem extending telescopically into said tubular mandrel in sealing, axially slidable, fluid communicating relationship with said mandrel and the drilling fluid passage in said stem.
 13. Joint according to claim 11 further including off axial actuating fluid passage means in said body connected to said off axial actuating fluid passage means in said stem and to said second means interconnecting said body and mandrel to apply axial force to said mandrel, the latter means being piston and cylinder means.
 14. Joint according to claim 13 including liner means in said body providing said axial passage therethrough and providing body portions of said first and second means interconnecting said body and mandrel, said off axial fluid passage means in said body lying between the inner periphery of said liner means and the inner periphery of said body.
 15. Joint according to claim 1 including tubular liner means inside said body connected to said body to prevent relative axial and rotational motion therebetween and providing said axial passage therethrough and providing body portions of said first and second interconnecting means.
 16. Joint according to claim 15 wherein said first means interconnecting said body and said mandrel includes splines on said liner means engaging splines on said mandrel.
 17. Joint according to claim 15 wherein said second means interconnecting said body and said mandrel includes piston means on said mandrel and cylinder means on said liner means and sliding seal means on said liner means engaging piston rod surface means on said mandrel.
 18. Joint according to claim 15 wherein said liner means includes portions of square cross-section outer periphery fitting snugly with portions of said body of square cross-section inner periphery.
 19. Joint according to claim 1 in combination with means to supply pressure fluid to said second means interconnecting the body and mandrel, a drill rig including means to rotate and suspend the driving joint, and means dependent on the load on said second connection means to control the supply of said pressure fluid to said second means interconnecting said body and mandrel.
 20. Combination according to claim 19 wherein said means to control the supply of said pressure fluid to said second means interconnecting the body and mandrel causes said second means interconnecting the body and mandrel to produce an axial force on said mandrel acting opposite to the load on said second connection means to maintain an adjustable selected load on said said second connection means.
 21. Joint according to claim 1 in combination with a power swivel connected to said first connection means.
 22. Joint according to claim 21 wherein both of said connection means are rotary shouldered connections.
 23. Joint according to claim 1 wherein said body is of kelly conformation on its exterior and in combination with a kelly bushing axially slidably mounted on said kelly adapted to transmit torque thereto.
 24. Joint according to claim 23 wherein at least the second one of said connection means is a rotary shouldered connection.
 25. In a rotary drilling apparatus, a string of drill pipe, a hoist carrying a swivel including a part rotatable relative to the hoist, and a combined driving joint and axial motion compensator means connected between the string of drill pipe and said rotatable part of the swivel to allow relative axial motion of the string of drill pipe and swivel and at the same time transmit fluid and axial force and torque therebetween, said combined driving joint and axial motion compensator means being disposed adjacent the swivel at the uppermost end of the string of drill pipe.
 26. In a rotary drilling apparatus, a string of drill pipe, a hoist carrying a swivel including a part rotatable relative to the hoist, a combined driving joint and axial motion compensator connected between the drill pipe and said rotatable part of the swivel to allow relative motion of the pipe and swivel and at the same time transmit fluid and force therebetween, said driving joint being disposed adjacent the swivel at the upper end of said drill pipe, said compensator means including piston and cylinder means transmitting axial load from the pipe to the rotatable part of the swivel, and means to maintain constant the force exerted by said piston and cylinder means and thereby to maintain constant tension on said hoist.
 27. In the method of drilling an earth bore from a floating platform thereabove with a rotary drilling apparatus, said apparatus including: on the platform a hoist having a movable portion movable up and down relative to the platform, in the earth bore a drill pipe with a drill bit at the lower end thereof, and means intermediate the drill pipe and said movable portion of the hoist providing a connection between the drill pipe and said movable portion of the hoist to take some of the weight of the pipe off the bit and providing for rotating tHe pipe and transmitting drilling fluid via the pipe between the upper end of the pipe and the drill bit, said method comprising: rotating the drill pipe, and via the drill pipe and the annulus thereabout circulating drilling fluid down to the drill bit and back up again, the improvement comprising: providing a hydraulic retractable telescopic driving joint in said connection between said movable portion of the hoist and the drill pipe applying to the telescopic driving point hydraulic fluid of a pressure equal to a prescribed pressure, and maintaining said pressure constant independent of rise and fall of said platform, whereby said movable portion of the hoist and any other portions of said drilling apparatus connected between said movable portion of the hoist and said joint move relative to the platform only the same as if there were no rise and fall of the platform.
 28. The combination of claim 25 wherein said driving joint is a kelly having exterior configuration means thereon for engaging with rotary drive means allowing torque transmission therethrough while permitting relative axial movement therebetween. 